Apparatuses and methods for cleaning test probes

ABSTRACT

Apparatuses and methods for cleaning test probes used in a semiconductor testing machine of the type having a plurality of test probes configured to contact the surface of a semiconductor wafer to test one or more dies formed thereon. In one embodiment, the apparatus includes a roller-support arm and a cylindrical roller supported by the roller-support arm. The roller has an outer surface comprising a sticky material. Debris on the probes will adhere to the sticky material as roller is rolled across tips of the probes. The probes are thereby cleaned.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/990,640, filed Nov. 16, 2004 (now U.S. Pat. No. 7,211,155), which isa divisional of U.S. patent application Ser. No. 09/986,751, filed Nov.9, 2001 (now U.S. Pat. No. 6,817,052).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to probe cards that are used toperform tests on semiconductor devices. The present invention moreparticularly relates to the cleaning of probe elements that extend fromsuch probe cards.

2. Background Art

Individual semiconductor (integrated circuit) devices (dies) aretypically produced by creating several identical dies on a semiconductorwafer, using known techniques of photolithography, deposition, and thelike. Generally, these processes are intended to create a plurality offully-functional integrated circuit devices, prior to singulating(severing) the individual dies from the semiconductor wafer. Inpractice, however, certain physical defects in the wafer itself andcertain defects in the processing of the wafer inevitably lead to someof the dies being “good” (fully-functional) and some of the dies being“bad” (non-functional). It is generally desirable to be able to identifywhich of the plurality of dies on a wafer are good dies prior to theirpackaging, and preferably prior to their being singulated from thewafer. To this end, a wafer “tester” or “prober” may advantageously beemployed to make a plurality of discrete pressure connections to a likeplurality of discrete connection pads (bond or contact pads) on thedies. In this manner, the semiconductor dies can be tested andexercised, prior to singulating the dies from the wafer. A conventionalcomponent of a wafer tester is a “probe card” to which a plurality ofprobe elements are connected—tips of the probe elements effecting thepressure connections to the respective pads of the semiconductor dies.

More specifically, in the typical wafer testing process, the probe cardis mounted to the prober, and probe elements (simply referred to as“probes”) extending from the probe card are brought into contact withpads formed on the dies of the wafer. In one process, electricalconnection of the prober and the pads is achieved by applying apredetermined pressure to the probes after the probes have been broughtinto contact with the pads so that the probes penetrate the materialforming the surface of the pads and come into low-resistance contactwith the portions forming the bodies of the pads. Such penetration ofthe pad surfaces produces debris (e.g., aluminum oxide chips). In a morepreferred process, used with probes that are elastic or springy,electrical connection of the prober and the pads can be achieved byapplying a predetermined pressure to the springy probes after the probeshave been brought in contact with the pads so that the probes arecompressed, making a solid electrical connection. When the probes arecompressed, a slight X and/or Y swipe is affected to the probes causinga portion of the material (e.g., an aluminum oxide film) forming thesurface of the pads to be scraped off. The scraping of the pad surfacesproduces debris (e.g., aluminum oxide chips).

Foreign matter including aluminum oxide chips (i.e., debris) adhering tothe dies and/or the probes may obstruct proper electrical connection.Various measures have been taken to prevent problems in achievingsatisfactory electrical contact.

In one conventional probe cleaning process, an abrading pad is used toremove foreign materials adhering to end portions (e.g., tips) of theprobes. The abrading pad can be composed of a mixture of an elastic basematerial and abrasive particles. Alternatively, the abrading pad can becomposed of tungsten carbide. Foreign materials adhering to the tips ofthe probes are scraped off the tips by repeating a cleaning cycle ofpressing-and-extracting the tips of the probes against (and possiblyinto) the pad. The pressing-and-extracting cleaning cycle includesmoving the abrading pad vertically (e.g., in the Z direction) againstthe probes, and then vertically away from the probes.

A disadvantage of the above described conventional cleaning process isthat the portions of the base material (e.g., silicon rubber) and/orabrasive particles (e.g., abrasive grains) may fall or chip off theabrading pad during the pressing-and-extracting process, therebyproducing additional foreign material that may stick to the probe tips.Further, foreign matter (previously removed from probe) that has fallenonto the abrading pad may later stick to the probes being cleaned.Accordingly, additional cleaning steps may be necessary to acceptablyclean the probes.

These additional steps may include blowing an organic solvent againstthe probes, and then blowing dry air against the probes. The use of suchsolvents is undesirable for many reasons. For example, the blowing of anorganic solvent is time consuming and potentially messy. Additionally,blowing of dry air is time consuming. Further, special equipment isrequired to blow the solvents and the dry air.

One attempt to improve upon the conventional process includes attachinga dust removing film to the top surface of the abrading pad. The purposeof the dust removing film is to confine foreign material, such as fineparticles of worn base material and fallen abrasive particles producedby the repetition of the pressing-and-extracting cleaning cycle, so thatthose foreign materials may not be discharged outside the dust removingfilm. For example, this process may not be useful for cleaning elasticor springy contact probes (often referred to as “spring contacts” or“contact springs”), such as those disclosed in U.S. Pat. No. 6,184,053,entitled “Method of Making Microelectronic Spring Contact Elements,”U.S. Pat. No. 5,476,211, entitled “Method for Manufacturing ElectricalContacts, Using a Sacrificial Member,” U.S. Pat. No. 5,917,707, entitled“Flexible contact structure with an electrically conductive shell,” U.S.Pat. No. 6,110,823, entitled “Method of modifying the thickness of aplating on a member by creating a temperature gradient on the member,applications for employing such a method, and structures resulting fromsuch a method,” U.S. Pat. No. 6,255,126, entitled “Lithographic contactelements”, and PCT Publication No. WO 00/33089, entitled ““Lithographiccontact elements,” all of which are incorporated herein by reference.

Another attempt to improve upon the conventional probe cleaning processincludes using a polymeric covered wafer to remove foreign materialsfollowing the pressing-and-extracting cleaning cycle described above.More specifically, the gel pad is positioned under the probes and thenbrought into contact with the probes (in a similar manner as thepressing-and-extracting using the abrading pad). The debris that hasbeen loosened by the abrading pad, or produced by the abrading pad,sticks to the gel pad and is thereby removed from the probes. Adisadvantage of this cleaning process is that an operator must typicallyswap the abrading pad with the gel pad during the cleaning process,because testing systems typically include only one auxiliary tray forholding such pads. This is undesirable because it prevents wafer testingfrom being a completely automated process, thereby significantlyreducing wafer testing throughput.

Accordingly, there is a need for improved methods and apparatuses forcleaning probes.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed to apparatuses and methods forcleaning test probes used in a semiconductor testing machine of the typehaving a plurality of test probes configured to contact the surface of asemiconductor wafer to test one or more dies formed thereon. The testprobes being cleaned can be any type of probe, such as tungsten needles,vertical probes, cobra probes, L-type probes, plunger probes, springprobes, contact bump probes formed on a membrane, etc.

In one embodiment, the apparatus of the present invention includes aroller-support arm, and a cylindrical roller supported by theroller-support arm. An outer surface of the roller comprises a stickymaterial. Debris on the probes will adhere to the sticky material asroller is rolled across tips of the probes.

The roller can comprise an inner cylindrical portion or core, and thesticky material can be disposed on a peripheral surface of the innercylindrical portion. The roller core spins about its longitudinal axis.Different portions of the sticky material engage against the tips of theprobes as the roller core spins. Friction between the sticky materialand the tips of the probes causes the roller core to spin as the armmoves in the horizontal direction.

According to an embodiment of the present invention, the roller-supportarm is pivotally connected to a wafer chuck of the testing machine. Thewafer chuck is typically used for supporting the semiconductor wafer tobe tested. An outer circumference of the roller is below a horizontalplane of the wafer when the roller-support arm is in a first position.This enables the wafer chuck to be maneuvered without the rollerengaging the probe tips. When the roller-support arm is moved to asecond position, at least a portion of the outer circumference of theroller is above the horizontal plane of the wafer and aligned with ahorizontal plane of the probe tips. When the arm is in the secondposition, the outer surface of the roller engages with and rolls acrossthe probes tips as the wafer chuck is moved in a horizontal direction.

According to another embodiment of the present invention, theroller-support arm is connected to some other maneuvering mechanism.That is, in another embodiment, the roller is connected in no way to awafer chuck.

In another embodiment of the present invention, the roller-support armextends between a pair of tracks. The sticky material engages the tipsof the probes as the arm moves horizontally along the tracks.

In an embodiment of the present invention, the apparatus for cleaningprobes also includes a loosening means for loosening debris from theprobes. The loosened debris can then be removed using the cylindricalroller having the sticky outer surface. More specifically, the looseneddebris will adhere to the sticky outer surface of the roller as it isrolled across tips of the probes.

The loosening means can include a second cylindrical roller having anabrasive outer surface. The debris is loosened from the probes as theouter surface of the second roller is rolled across the tips of theprobes.

The loosening means can alternatively include a block having an abrasivetop surface. The debris is loosened from the probes as the abrasive topsurface of the block is moved in a horizontal direction along the tipsof the probes.

In another embodiment the loosening means includes an abrading pad.Debris is loosened from the probes as the abrading pad is repeatedlymoved in a vertical direction against and away from the tips of theprobes.

In an alternative embodiment, the loosening means includes a secondcylindrical roller having a bristled outer surface. Debris is loosenedfrom the probes as the outer surface of the second roller is rolledacross the tips of the probes.

In still another embodiment, the loosening means comprises a blockhaving a bristled top surface. Debris is loosened from the probes as thebristled top surface of the block is moved in a horizontal directionalong the tips of the probes.

In another embodiment, the apparatus for cleaning of probes includes aroller having an electrostatic outer surface. An arm for supports theroller and engages the roller against tips of the probes. Debrisadhering to the tips of the probes is transferred to the electrostaticouter surface of the roller as it is rolled along the tips of theprobes.

A method for cleaning test probes, according to an embodiment of thepresent invention, includes the step of maneuvering a cylindrical rollerhaving a sticky outer surface such that the sticky outer surface isengaged against tips of the probes. The sticky outer surface is thenrolled along the tips of the probes to thereby transfer debris adheringto the probes to the sticky outer surface.

Prior to engaging the sticky outer surface of the roller against thetips of the probes, it may be beneficial to first loosen the debris. Thedebris can be loosened by scraping the tips of the probes against anabrasive surface. This can be accomplished by maneuvering a secondcylindrical roller having an abrasive outer surface such that theabrasive outer surface is engaged against the tips of the probes. Theabrasive outer surface is then rolled along the tips of the probes tothereby loosen the debris from the probes.

The debris can alternatively be loosened by repeatedly moving anabrasive surface in a vertical direction against and away from the tipsof the probes to thereby loosen the debris from the probes.

In another embodiment, the debris is loosened by maneuvering a secondcylindrical roller having a bristled outer surface such that thebristled outer surface is engaged against the tips of the probes. Thebristled outer surface is then rolled along the tips of the probes tothereby loosen the debris from the probes.

Alternatively, a bristled surface can be moved in a horizontal directionalong the tips of the probes to thereby loosen the debris from theprobes.

In another embodiment, the method for cleaning test probes includes thestep of maneuvering a cylindrical roller having a electrostatic outersurface such that the electrostatic outer surface is engaged or nearlyengaged against tips of the probes. The electrostatic outer surface isthen rolled along the tips of the probes to thereby transfer debrisadhering to the probes to the electrostatic outer surface.

Further features and advantages of the present invention, as well as thestructure and operation of various embodiments of the present invention,are described in detail below with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate various exemplary embodiments of thepresent invention and, together with the description, further serve toexplain the principles of the invention and to enable a person skilledin the pertinent art to make and use the invention. In the accompanyingdrawings:

FIG. 1 is a side view of exemplary testing environment in which thepresent invention is useful;

FIGS. 2A and 2B are side views of the exemplary testing environment ofFIG. 1, with a roller embodiment of the present invention incorporatedtherewith;

FIG. 3 is a perspective view of the exemplary testing environment ofFIG. 1, with a roller embodiment of the present invention incorporatedtherewith;

FIGS. 4A and 4B illustrate an embodiment of the present invention thatincorporates multiple rollers;

FIG. 5 illustrates an embodiment of the present invention where rollersare attached to a maneuvering mechanism other than a wafer chuck;

FIGS. 6A and 6B, respectively, illustrate an abrasive block and abristled block, that can be used to loosen debris from probes, accordingto embodiments of the present invention;

FIG. 7 illustrates an alternative embodiment for maneuvering the rollersof the present invention;

FIG. 8 is a flow diagram useful for describing the operation ofembodiments of the present invention; and

FIG. 9 illustrates an embodiment of the present invention in which asticky material, that can be used to clean tips of probes, is exposedbetween a pair of rollers.

DETAILED DESCRIPTION OF THE INVENTION

The following description is of the best modes presently contemplatedfor practicing the invention. This description is not to be taken in alimiting sense but is made merely for the purpose of describing thegeneral principles of the invention. The scope of the invention shouldbe ascertained with reference to the claims. In the description of theinvention that follows, like numerals or reference designators will beused to refer to like parts or elements throughout.

FIG. 1 is a side view of a portion of an exemplary probing-test system100 that includes a probe card 102, a test head 106 (also known as aprobe head), a wafer chuck 112, and a translation mechanism 114. One ofordinary skill in the art will appreciate that these elements have notbeen drawn to scale. For example, the pitch of probes elements 104extending from probe card 102 may be such that hundreds or thousandsprobe elements 104 may extend from probe card 102.

A semiconductor wafer 110 is supported by wafer chuck 112 (also know asa wafer stage, prober stage, or wafer holding table). Translationmechanism 114 displaces (i.e., maneuvers) wafer chuck 112 in X, Y, Zand/or θ directions as required. Translation mechanism 114 includes oris attached to an actuator type device that imparts the displacement.Wafer 110 includes a plurality of dies (not shown) formed byphotolithography, deposition, diffusion, and the like, on its topsurface. Each die (e.g., chip or device pattern) typically has a numberof electrode contact areas, e.g., bond or contact pads (not shown),which may be disposed at any location and in any pattern on the surfaceof the die. Note that the terms “die” and “dice” are used throughout thespecification to refer to both unsingulated die and dice, that is, a dieor dice in wafer form, and individual, singulated die or dice.Typically, these dies are fabricated to be identical to one another.However, as is known, flaws in either wafer 110 itself or in any of theprocesses to which wafer 110 is subjected to form the dies, can resultin certain dies being non-functional, according to well established testcriteria.

Probe card 102 is shown above wafer chuck 112. A plurality of probeelements 104 (simply referred hereafter as “probes”) extend from probecard 102. Examples of probes 104 include tungsten needles, verticalprobes, cobra probes, L-type probes, plunger probes, and elastic orspring probes (such as those disclosed in the patents that wereincorporated by reference above). Probes 104 make contact with thecontact areas (e.g., bond or contact pads) of the dies when wafer 110 isappropriately maneuvered by wafer chuck 112. More specifically, endportions (e.g., tips) of probes 104 make contact with the contact areason the dies so that an electrical connection is made. Accordingly, thedies of wafer 110 and the test head 106 can be electrically connectedthrough probes 104 by moving chuck 112 upward to cause the electrodepads on the dies to contact probes 104. Tests (e.g., burn-in tests) ofthe dies can then be performed. Probes may also contact sacrificial padsof a scribe sheet.

When pressure is applied to probes 104, bringing probes 104 into contactwith electrode pads, foreign matter chips or particles adhering to thedies and/or probes 104 can obstruct the electrical connections.Additionally, such foreign matter chips or particles (referred tocollectively hereafter as “debris”) originally located on the die may betransferred to probes 104. Examples of debris that may adhere to probes104 include: aluminum, aluminum oxide, copper, chrome, gold, polyamide,titanium metal, titanium nitride, tungsten, silicon, silicon oxide,phosphor, boron and any other materials from which the dies areproduced. Sometimes, even things such as dust, hair, skin, dirt and/orclothing particles may adhere to probes 104. Indeed, any material thatis in a semiconductor fabrication area may become attached to theprobes.

The present invention relates to improved methods and apparatuses forremoving (i.e., cleaning) such debris from probes 104.

FIGS. 2A, 2B and 3 illustrate a first embodiment of the presentinvention. As shown in FIG. 2A, a first end of a support arm 202 ispivotally attached to wafer chuck 112. At an opposite or second end ofarm 202, a roller 204 is supported. For example, roller 204 can bepivotally attached to arm 202 at the second end of arm 202.Alternatively, roller 204 can slide onto a shaft or bar (not shown)extending perpendicularly (e.g., in the Y direction, shown in FIG. 3)from the second end of arm 202. These are just of few examples of howarm 202 can support roller 204, and thus, are not meant to be limiting.Ball bearings can optionally be used to enable roller 204 to smoothlyspin or turn as an outer surface 302 (shown in FIG. 3) of roller is incontact with and moved along tips of probes 104, as described below.

When arm 202 is in a first position, as shown in FIG. 2A, an outer mostcircumference 206 of roller 204 is below a horizontal plane 210 of wafer110. While arm 202 is in the first position, translation mechanism 114and wafer chuck 112 can be used to maneuver wafer 110 such that wafer110 is appropriately aligned under probes 104 protruding from probe card102. At that point, translation mechanism 114 and wafer chuck 112 canmaneuver wafer 110 in an upward vertical direction (e.g., the Zdirection) until probes 104 make contact with the contact areas on thedies of wafer 110 so that electrical connections are made, as shown inFIG. 2A. Once the electrical connections are made, appropriate testingof the dies of wafer 110 can be performed. Accordingly, neither arm 202nor roller 204 interfere with the normal testing of the dies when arm202 is in the first position.

When arm 202 is moved to a second position, as shown in FIG. 2B, atleast a portion of the outermost circumference 206 of roller 204 isabove horizontal plane 210 of wafer 110. FIG. 3 shows a perspective viewof roller 204, when arm 202 is in the second position. Additionally,when arm 202 is in the second position, outermost circumference 206 ofroller 204 should be aligned with a horizontal plane 208 formed by thetips of probes 104. This will cause an outer surface 302 (shown in FIG.3) of roller 204 to make contact with the tips of probes 104 when waferchuck 112 moves in a horizontal direction (e.g., the X direction), as isshown in FIGS. 2B and 3.

Outer surface 302 of roller 204 should be sticky enough to remove debrisfrom probes 104. Accordingly, roller 204 may also be referred to hereinas a “sticky roller”. Preferably, outer surface 302 of roller 204 shouldalso be stable enough that it does not produce new debris that may stickto probes 104. In other words, outer surface 302 of roller 204 shouldgenerally resist transferring material to probes 104. The only materialtransfer should be from probes 104 to outer surface 302 of roller 204.Outer surface 302 of roller 204 can be made from any material orcombinations of materials that exhibit the above described desiredproperties. Exemplary materials that can be used to produce outersurface 302 include, but are not limited to: polymeric materials,silicone, urethane and acrylic.

Outer surface 302 of roller 204 can have additional desirableproperties. For example, roller 204 is preferably elastomeric so that itdoes not damage probes 104 when roller 204 is moved along the tips ofprobes 104.

In an alternative embodiment, rather than being sticky, outer surface302 of roller 204 is made from an electrostatic material that canelectrostatically remove debris from probes 104.

According to an embodiment of the present invention, rather than being asticky material, outer surface 302 includes a material with micro-porescontaining a cleaning agent (e.g., a basic or acidic cleaner).Accordingly, the tips of the probes can be cleaned by the cleaning agentas the outer surface of the roller as is rolled along the tips of theprobes.

When arm 202 is in the second position, and wafer chuck 112 moves in ahorizontal direction (e.g., the X direction), outer surface 302 ofroller 204 engages (i.e., come into contact with) the tips of probes104, as shown in FIGS. 2B and 3. Loose debris adhering to probes 104(e.g., debris electrostatically stuck to probes 104) thereby comes intocontact with and sticks to outer surface 302 of roller 204. Probes 104are thereby cleaned. As wafer chuck 112 continues to move in thehorizontal direction, friction between outer surface 302 of roller 204and the tips of probes 104 causes roller 204 to turn about its pivotalconnection to arm 202. This friction between roller 204 and probes 104,which is much less than it would be if a non-pivoting surface werescraped along the tips of probes 104, is not enough to cause probes 102to gouge into the outer surface of roller 204. Thus, neither roller 204nor probes 104 are damaged by this cleaning procedure.

In an alternative embodiment, rather than being pivotally connected,support arm 202 is in a fixed position that is offset from the top ofwafer chuck 112, for example, fixed in the position shown in FIG. 2B.

A vertical (e.g., in the Z direction) contact force of, for example,approximately 15 grams (including as little as 2 grams or less and asmuch as 150 grams or more) may be desired between roller 204 and probes104 to ensure that debris sticks to roller 204.

Arm 202 can be maneuvered from the first position to the second position(or from the second position to the first position) in any appropriatemanner. For example, arm 202 can be spring loaded in the direction shownby arrow 212 to allow for cleaning pressure control. In another example,an electric motor can be used to maneuver arm 202. Alternatively, arm202 can be pneumatically driven. In still another example, hydraulicscan be used to maneuver arm 202. These examples are not meant to belimiting.

As shown in FIG. 3, more than one arm 202 can be used to support roller204. For example, roller 204 can be pivotally connected at one of itslongitudinal ends to first arm 202 a and at its other longitudinal endto second arm 202 b. Alternatively, a bar or shaft (not shown) canextend between arms 202 a and 202 b in a perpendicular direction (e.g.,the Y direction) from each of arms 202 a and 202 b. Roller 204 can restabout the bar or shaft.

As shown in FIG. 3, arms 202 a and 202 b are optionally gimbal mountedto allow for accommodation of a non-planar relationship between rollersurface 302 and plane 208 of probe tips 104. An arrow 306 illustrates apossible pivot direction if arms 202 a and 202 b were supported by anexemplary gimbal mount 304.

Roller 204 is preferably cylindrical, as can be seen in FIG. 3. Innerportions of roller 204 can be made from any number of materials, so longas outer surface 302 of roller 204 exhibits the desired properties. Forexample, an inner or core portion of roller 204 can be made of aninexpensive hard plastic material, and a sheet of material exhibitingsome or all of the above described desired properties can be adhesivelydisposed on a peripheral surface of the core material.

In one embodiment of the present invention, a plurality of sheets ofmaterial having the desired properties are disposed one above the othersuch that each sheet sticks to a sheet of a previous layer. After a topsheet has been sufficiently covered with debris from cleaning probes,the top sheet can be pealed off such that a clean sheet of the previouslayer becomes the top sheet.

In another embodiment, a cylindrical sleeve is used. The sleeve is sizedso that the sleeve can be removably inserted or slid over a core ofroller 204. The sleeve has disposed about its outer surface one or moresheets of material having the sticky property described herein. When thesleeve is about the core of roller 204, outer surface 302 of roller 204is the outer surface of the sleeve.

When necessary, roller 204 can be replaced by an operator.Alternatively, spare rollers 204 can be stored at a location that allowsarm 202 to automatically swipe out a used roller 204 and load in a cleanroller 204. For example, spare rollers can be stored in a rack (notshown). Arm 202 can replace a roller with another roller from the rackwhen appropriate. In such an embodiment, it is beneficial that arm 202be an articulating arm that can further pivot about a mid portion of thearm. This would provide arm 202 will an increased range of motion. Therollers in the rack can all be identical to one another. Alternatively,different types of rollers can be stored in the rack. For example, somerollers 204 may have an abrasive outer surface that is used to loosendebris from tips of probes 104. Other rollers 204 may have a stickyouter surface that is used to remove loosened debris. An articulatingarm 202 can first obtain an abrasive roller 204 from the rack to loosendebris. Arm 202 can then replace the abrasive roller 204 with a stickyroller to remove the loosened debris.

Similarly, when a sleeve is used, the sleeve can be replaced by anoperator by sliding the sleeve off a core of roller 204, and sliding anew sleeve onto the core. This operation of replacing the sleeve canalternatively be automated as just discussed above (e.g., a rack is usedto store spare sleeves that can be obtained by an articulating arm 202).

Roller 204 of the present invention can be used to improve upon priorcleaning processes. For example, debris on probes 104 can first beloosened by pressing-and-extracting the tips of probes 104 against anabrading pad. The abrading pad can be made from a mixture of an elasticbase material and abrasive particles. Alternatively, the abrading padcan be made from tungsten carbide or any other appropriate materialwhose hardness is substantially similar to the hardness of the probetips. This will enable the abrading pad to loosen debris from tips ofprobes 104, while limiting any damage to probes 104. Debris adhering tothe tips of probes 104 are scraped off or loose by repeating a cleaningcycle of pressing-and-extracting the tips of the probes against (andpossibly into) the abrading pad. After the debris has been loosened bythe pressing-and-extracting process, roller 204 of the present inventioncan be used to remove the loosened debris from the tips of probes 104,as described above. Accordingly, the present invention enables automatedremoval (i.e., without operator intervention) of the loosened debrisfrom probes 104.

Use of roller 204 is very advantageous even if the tips of probes 104are not first scraped or scrubbed by an abrading pad. For example, useof roller 204 without first scraping tips of probes 104 will stillremove a majority of the loose debris adhering to probes 104.Accordingly, use of roller 204 will improve electrical contact betweenprobes 104 and electrodes on dies of wafer 110 even when probes 104 arenot first scraped. Further, the use of roller 204 is very practicalwhere optical recognition sensors, e.g., cameras (not shown), are usedto make sure probes 104 are appropriately aligned with electrodes ondies of wafer 110. Depending on the lighting techniques employed, loosedebris on the tips of probes 104 may prevent the optical sensors fromrecognizing probes 104. Even without first scraping or scrubbing probes104, roller 204 will remove enough loose debris from probes 104 so thatthe optical recognition sensors can recognize probes 104 and accuratelyperform their function.

Roller 204 of the present invention can also be used to clean contactbumps of probe membranes that are used in some wafer testers, such asthose discussed in U.S. Pat. No. 5,422,574, entitled “Large ScaleProtrusion Membrane For Semiconductor Devices Under Test With Very HighPin Counts,” which is incorporated herein by reference.

A longitudinal length (e.g., the Y directional length) of roller 204 ispreferably longer than the area of probe card 102 from which probes 104protrude. Stated another way, roller 204 is preferably wide enough toclean all probes 104 of probe card 102 with one directional roll ofroller 204. Alternatively, if roller 204 is not wide enough to clean allprobes 104 with one roll, multiple rolls may be necessary.

In the above described embodiments, roller 204 is described as beingmoved with respect to test head 106. Alternatively, test head 106 can bemoved with respect to roller 204 to thereby engage roller 204 againstprobes 104. Further, movement of roller 204 relative to test head 106during probe cleaning can be in an X direction and/or a Y direction. Onepass or multiple passes may be made in any pattern.

In another embodiment, a motor connected to arm 202, or within roller204, causes roller 204 to spin even when roller 204 is not rolled alongtips of probes 104. Thus, roller 204 can be spun against a specificportion of probe card 102 even when the roller is not moving in an X, Yor Z direction with respect to probe card 102.

In another embodiment, a region of outer surface 302 is a stickymaterial and another region is an abrasive material that is used toloosen debris. For example, 180 degrees of outer surface 302 is sticky,and the remaining 180 degrees of outer surface 302 is an abrasive. Ofcourse, this example is not meant to be limiting. This embodiment isespecially useful if roller 204 is spun by a motor.

Referring now to FIGS. 4A and 4B, a plurality (i.e., two or more)rollers 204 a and 204 b can be used to clean probes 104. In FIG. 4A, arm202 is in a first position such that the outer circumferences of rollers204 a and 204 b are below horizontal plane 210 of wafer 110. In FIG. 4B,arm 202 is in a second position such that at least a portion of theouter circumferences of rollers 204 a and 204 b are above plane 210 andcan contact probes 104 when wafer chuck 112 is moved in the horizontaldirection (e.g., the X direction).

In one embodiment, the two rollers 204 a and 204 b are essentiallyidentical in that they are both sticky rollers. Accordingly, followingroller 204 b would remove any debris possibly missed by leading roller204 a.

In another embodiment, leading roller 204 a has an abrasive outersurface, for example, a surface made from tungsten carbide. Such aroller is thus also referred to herein as an “abrasive roller”. In thisembodiment, the abrasive roller (e.g., roller 204 a) is used to loosendebris from probes 104. The abrasive roller can be made from any otherappropriate material (e.g., tungsten carbide) whose hardness ispreferably substantially similar to the hardness of the probe tips. Thiswill enable the abrasive roller to loosen debris from tips of probes 104while limiting damage to probes 104. The following roller (e.g., roller204 b), which is a sticky roller, is then used to remove the looseneddebris from probes 104.

Both rollers 204 a and 204 b can be supported by a common arm 202, asshown in FIGS. 4A and 4B. Alternatively, rollers 204 a and 204 b caneach be supported by its own dedicated arm (as shown in FIG. 5).

Preferably, when arm 202 is in the second position, and the abrasiveroller (e.g., roller 204 a) is engaged against (i.e., in contact with)probes 104, the abrasive roller is vertically offset from (i.e., notabove) wafer 110, as shown in FIG. 4B. This will prevent debris loosenedby the abrasive roller from possibly falling onto wafer 110.

In one embodiment, leading roller 204 a has a bristled outer surfacerather than an abrasive outer surface. The bristles of the roller areused to loosen debris from tips of probes 104.

In another embodiment, leading roller 204 a is replaced by an abrasiveblock 604 (e.g., as shown in FIG. 6A) that does not spin or roll. A topsurface 606 is preferably rounded, as shown in FIG. 6A. When arm 202 isin the second position, and top surface 606 of abrasive block 604 isengaged against probes 104, the tips of probes 104 will scrape againsttop surface 606 as wafer chuck 112 is moved in a horizontal direction(e.g., the X direction), thereby loosening debris. In still anotherembodiment, leading roller 204 a is replaced by a block 614 having abristled top surface 616, as shown in FIG. 6B. When arm 202 is in thesecond position, and bristled top surface 616 of block 614 is engagedagainst probes 104, the bristles loosen debris from tips of probes 104as wafer chuck 112 is moved in a horizontal direction (e.g., the Xdirection). In either embodiment, a sticky following roller (e.g.,roller 204 b) is preferably used to remove the loosened debris fromprobes 104. Each supporting arm 202 a and 202 b is optionallyindependently suspended (e.g., using independent springs) to provideindependent suspension for blocks 604 or 614.

In the above described embodiments, roller 204(s) (and possibly blocks,e.g., 604 or 614) is/are described as being supported by one or morearms 202 that is/are pivotally attached to wafer chuck 112. Arm(s) 202can alternatively be attached to some other maneuvering mechanism 502(other than wafer chuck 112) capable of appropriately maneuveringroller(s) 204 (and possibly blocks, e.g., 604 or 614). In oneembodiment, arm(s) 202 are pivotally attached to maneuvering mechanism502 and roller(s) 204 (and possibly blocks, e.g., 604 or 614) can beengaged against probes 104 in a manner similar to that discussed above.In another embodiment, arm(s) 202 and maneuvering mechanism 502 areintegrally formed, rather than pivotally connected. The point is,roller(s) 204 (and possibly blocks, e.g., 604 or 614) need not beattached in any way to wafer chuck 112.

In one embodiment, roller 204 is supported by a bar 702 (which is animplementation of arm 202) that extends between a pair of tracks 704, asshown in FIG. 7. Tracks 704 can be attached to opposite sides of a testchamber of the wafer testing system such that roller 204 is at theappropriate vertical (e.g., Y) height. When bar 702 is moved alongtracks 704 in the vertical direction 706 (e.g., the X direction) by anappropriate means, outer surface 302 of roller 204 engages with androlls across the tips of probes 104, thereby cleaning probes 104. Morethan one bar 702, and thus, more than one roller 204, can be supportedby tracks 704. A first roller can be an abrasive or bristled roller 204that is followed by a sticky roller 204. Similarly, a non rollingabrasive or bristled block (such as those shown in FIGS. 6A and 6B,respectively) can be followed by a sticky roller 204. Each of track 704can be attached to a respective side of the test chamber in such a waythat independent suspension (e.g., in the Z direction) is provided foreach end of bar 702.

FIG. 8 is a flow diagram useful for describing operation of the variousembodiments of the present invention. More specifically, FIG. 8 can beused to describe methods for cleaning test probes 104 configured tocontact the surface of a semiconductor wafer 110 to test one or moredies formed thereon. According to an embodiment of the presentinvention, the method includes at a step 804, maneuvering a cylindricalroller 202 having an outer surface 302 possessing desirable properties,such that the outer surface 302 is engaged against the tips of theprobes 104. At a next step 806, the outer surface is rolled along thetips of the probes to thereby transfer debris adhering to the probes tothe outer surface of the roller.

As described above, a desirable property of outer surface 302 of roller202 is that it is sticky, such that debris adhering to probes 104 willbe transferred from probes 104 to sticky outer surface 302 as it isrolled across the tips of probes 104. Another desired property of outersurface 302 is that it is stable enough that there is little to nomaterial transfer of portions of outer surface 302 (e.g., chips orparticles of outer surface 302) to probes 104. Preferably, materialtransfer is generally limited to transfer from probes 104 to outersurface 302. Other desirable properties of a sticky outer surface 302are discussed above.

As described above, more than one sticky roller 202 can be used to cleanprobes 104. Accordingly, steps 804 and 806 can be repeated using, forexample, a second sticky roller to thereby remove any debris not removedby a first sticky roller 202.

In another embodiment, also mentioned above, the outer surface 302 ofroller 202 is made from a material that can electrostatically removedebris from probes 104.

In another embodiment, debris is loosening from the probes 104 at a step802 (shown in dashed line), which is performed prior to step 804. Asexplained above, debris can be loosened in a number of different ways.For example, a roller 202 having an abrasive outer surface (i.e., anabrasive roller 202) can be engaged against the tips of the probes andthen rolled across the tips of the probes to thereby loosen debris. Inanother embodiment, a bristled roller 202 is used in place of theabrasive roller 202. In other embodiments, both of which are describedabove, a non rolling abrasive block, or bristled block, is moved in ahorizontal direction along the tips of probes 104. In still anotherembodiment, also described above, an abrading pad is repeatedly movevertically against and away from the tips of probes 104 to therebyloosen debris from probes 104.

Embodiments of the present invention can also be used in various othertypes of probing-test systems. For example, embodiments of the presentinvention can be used in a probing-test system that has an arrangementwhere probe card 102 and wafer 110 are vertically oriented. In thisarrangement, wafer 110 (and/or probe card 102) are moved in a horizontaldirection (e.g., the X or Y direction) until probes 104 make contactwith the contact areas on the dies of wafer 110 so that electricalconnections are made. In another type of probing-test system, thepositions of wafer 110 and probe card 102 (as shown, for example, inFIGS. 1, 2A, 2B, 4A and 4B) are reversed.

Another embodiment of the present invention is described with referenceto FIG. 9. At least a two rollers 904 a and 904 b support a sheet ofmaterial 906 having a top surface that is sticky. Accordingly, thissheet of material 906 is also referred to as “sticky sheet” 906. Rollers904 a and 904 b are attached to a maneuvering mechanism 902 capable ofappropriately maneuvering rollers 904 a and 904 b and sheet 906 thatextends there-between. More specifically, maneuvering mechanism 902 canbe used to move sticky sheet 906 underneath probe card 102, and thentoward probe card 102 until tips of probes 104 engage against stickysheet 906. Alternatively, probe card 102 is moved against sticky sheet906. Debris adhering to tips of probes 104 is thereby transferred tosticky sheet 906. When appropriate, roller 904 a and/or roller 904 b isspun (in a clockwise or counterclockwise direction) manually orautomatically (e.g., by a motor). This causes a dirty portion of stickysheet 906 to be rolled up (e.g., about one of rollers 902 a and 902 b)and a clean portion of sticky sheet 906 to be rolled out (e.g., from theother one of rollers 902 a and 902 b) and thereby exposed.

In many embodiments described above, a roller 204 having a sticky outersurface 302 is used to clean debris from tips of probes 104 of a probecard 102. Alternatively, a roller 204 having a sticky outer surface 302can be used to clean debris from a wafer 110. This can be especiallyuseful for cleaning debris from the type of wafer including dies havingextending spring like contacts. More specifically, this can beespecially useful for removing debris that adheres to spring likecontacts that extend from dies of a wafer. Additionally, debris adheringto such spring like contacts can initially be loosened using variousembodiments discussed above. In wafer cleaning embodiments, an arm 202that supports a sticky roller 204 (and/or an abrasive roller or othersurface) can be connected to test head 106, or some other location, sothat roller 204 can be maneuvered such that its outer surface 302 isengaged against wafer 110 (or wafer 110 can be maneuvered so that it isengaged against outer surface 302 of roller 204).

The previous description of the preferred embodiments is provided toenable any person skilled in the art to make or use the presentinvention. While the invention has been particularly shown and describedwith reference to preferred embodiments thereof, it will be understoodby those skilled in the art that various changes in form and details maybe made therein without departing from the spirit and scope of theinvention.

1. An apparatus for cleaning comprising: a loosening means for looseningdebris from electrically conductive probes extending from a probe cardand comprising contact tips for contacting and establishing electricalconnections with semiconductor dies; and a roller having an outersurface comprising a sticky material, wherein the loosened debris willadhere to the sticky material as the outer surface of the roller isrolled across the tips of the probes.
 2. The apparatus of claim 1,wherein the loosening means comprises a second roller having a bristledouter surface, and wherein the debris is loosened from the probes as theouter surface of the second roller is rolled across the tips of theprobes.
 3. The apparatus of claim 1, wherein the loosening meanscomprises a block having a bristled top surface, and the debris isloosened from the probes as the bristled top surface of the block ismoved in a horizontal direction along the tips of the probes.
 4. Anapparatus for cleaning probes that extend from a probe card used fortesting one or more semiconductor dies, comprising: a loosening meansfor loosening debris from the probes; and a roller having an outersurface comprising a sticky material, wherein the loosened debris willadhere to the sticky material as the outer surface of the roller isrolled across tips of the probes, wherein the loosening means comprisesa second roller having an outer surface comprising an abrasive material,and wherein the debris is loosened from the probes as the outer surfaceof the second roller is rolled across the tips of the probes.
 5. Anapparatus for cleaning probes that extend from a probe card used fortesting one or more semiconductor dies, comprising: a loosening meansfor loosening debris from the probes; and a roller having an outersurface comprising a sticky material, wherein the loosened debris willadhere to the sticky material as the outer surface of the roller isrolled across tips of the probes, wherein the loosening means comprisesa block having an abrasive top surface, and the debris is loosened fromthe probes as the abrasive top surface of the block is moved in ahorizontal direction along the tips of the probes.
 6. An apparatus forcleaning probes that extend from a probe card used for testing one ormore semiconductor dies, comprising: a loosening means for looseningdebris from the probes; and a roller having an outer surface comprisinga sticky material, wherein the loosened debris will adhere to the stickymaterial as the outer surface of the roller is rolled across tips of theprobes, wherein the loosening means comprises an abrading pad, and thedebris is loosened from the probes as the abrading pad is repeatedlymoved in a vertical direction against and away from the tips of theprobes.